The invention relates to a detector unit which is designed for connection to an optical bus which is formed by detector units of the same type arranged adjacently.
Such detector units serve, for example, as sensor devices, in particular as light barriers, diffuse sensors, inductive proximity switches, capacitive proximity switches or ultrasonic sensors. In some applications a plurality of such detector units are used in a close spatial arrangement to pick up a plurality of measurement values simultaneously. A common control of these detector units and a data flow between the detector units among one another is required here. For this purpose, the detector units are connected to a common data bus.
It is known for the forming of this data bus to provide a galvanic plug connection between the adjacent detector units. Such a connection, however, has an insufficient protection category for some applications.
Detector units have therefore been developed for demands with a higher protection category which have a respective optical interface and an associated photoelectrical transceiver at two opposing housing sides, with the optical interfaces of two adjacent detector units being provided in a congruent arrangement. An optoelectronic bus, which allows a bidirectional communication between the adjacent detector units, is thereby formed via the two photoelectrical transceivers electrically connected to one another and the associated optical interfaces of this detector unit with adjacent detector units.
A disadvantage of this design lies in the fact that the data communication, in particular the synchronization, takes a response time which is undesirably long for some applications since a signal to be transmitted along the formed bus has to be transformed, starting from an optical signal, into an electrical signal and back into an optical signal within each detector unit. Moreover, the design of the detector units explained is comparatively complex and therefore undesirably expensive.